Field of the Invention
The present invention relates in one embodiment to controlling acoustic howling feedback in audio signals.
Description of the Related Art
In the public addressing (PA) or other audio systems, an annoying howling sound will be produced if the gain between the speaker(s) and microphone(s) is larger than one and they are in phase. Traditionally, such howling can be removed by manually repositioning the microphone and/or speaker. Alternatively, the howling can be eliminated by adjusting the gain in different audio bands using an EQ filter. However, such methods are not convenient and/or are impractical in some situations. For example, if the position of microphone and speaker is fixed and/or an EQ filter is not available, the above methods cannot be employed. Although there are several prior art descriptions regarding the elimination of the howling digitally, such prior art descriptions are flawed in one or more of the following ways: howling frequency cannot be estimated accurately, especially using limited number points of fast Fourier transform (FFT) and thus the howling is not removed efficiently and reliably; tonal music signals are prone to be removed wrongly; processed signals are distorted; or processed signals are too complicated to be implemented in embedded system and thus consume more memory or MIPs than desired. What is needed is an improved system and method for handling howling sounds.